Field of the Invention
The invention relates to a display system having a display that is controlled by a display controller that in turn is driven by a picture controller. A system clock pulse is provided to a picture signal source that feeds a picture signal to the picture controller that gets displayed on the display in dependence on the system clock pulse.
Display systems are used to display pictures using a video signal or a television signal such as, NTSC or PAL standard, liquid crystal displays (LCD) being used, for example.
European Patent EP 0 489 757 B1 discloses a clock-controllable driving unit, constructed as an integrated circuit, of a display system in which a plurality of identically constructed integrated circuits are provided for art of the display in each case. A character generator is provided which, after the inputting of a code, reads output signals from a storage unit which are displayed on the display.
In the context of displaying pictures according to a television standard (NTSC, PAL), in the course of displaying a picture to be displayed on the display, synchronization between the display system and the picture source is performed after each picture line. With the result that a phase shift between the clock frequency of the display system and the frequency of the picture signal fed in occurs within a picture line. This leads to picture blur and to shadow effects at vertical edges.
It is accordingly an object of the invention to provide a display system and method for supplying a display system with a picture signal which overcome the above-mentioned disadvantages of the prior art devices and methods of this general type, in which the picture quality is improved and a reduction in particular shadow effects and picture blur is achieved.
With the foregoing and other objects in view there is provided, in accordance with the invention, a display system, including: a display; a display controller controlling the display; a picture controller connected to the display controller and operating in dependence on a system clock pulse, the system clock pulse defining a time response of picture pixels within a line; and a picture signal source connected to the picture controller and receiving the system clock pulse, the picture signal source feeding a picture signal to the picture controller in dependence on the system clock pulse so that the picture controller displays the picture signal on the display via the display controller in dependence on the system clock pulse.
A particularly good picture quality is achieved if the picture signal fed in is synchronized as a function of the system frequency of the display system.
In accordance with an added feature of the invention, the picture controller samples the picture signal with a sampling clock pulse that is dependent on the system clock pulse and results in a sampled picture signal, the picture controller initiates a display of a corresponding pixel on the display in accordance with the sampled picture signal, and the picture signal source feeding the picture signal to the picture controller with regard to the sampling clock pulse with a predeterminable phase shift.
In accordance with another feature of the invention, the predetermined phase shift is constant for at least one picture line of the display.
In accordance with another feature of the invention, there is a control unit and a second picture signal source connected to the picture controller, the second picture signal source feeding a further picture signal to the picture controller, the control unit receiving the system clock pulse and outputting a changeover signal to the picture controller, the changeover signal having a further predeterminable phase shift relative to the system clock pulse and defining which of the picture signal and the further picture signal is displayed on the display by the picture controller.
In accordance with a further added feature of the invention, the picture controller samples the picture signal with a sampling clock pulse that depends on the system clock pulse and results in a sampled picture signal, the picture controller initiating a display of a corresponding pixel on the display in accordance with the sampled picture signal, the picture signal source feeding the picture signal to the picture controller with regard to the sampling clock pulse with a predeterminable phase shift, the control unit sampling the system clock pulse at a sampling frequency whose reciprocal value is not equal to a multiple of a time period of the system clock pulse, and the control unit specifies the predetermined phase shift as a multiple of the reciprocal value of the sampling frequency.
With the foregoing and other objects in view there is further provided, in accordance with the invention, a method for supplying a picture signal, which includes: displaying a picture signal on a display of a display system in dependence on a system clock pulse, the system clock pulse defining a time response of picture pixels within a line; and feeding the picture signal to the display from a picture signal source in dependence on the system clock pulse.
In accordance with an added feature of the invention, there are the steps of: specifying the picture signal for at least one first picture pixel; subsequently specifying the picture signal for at least one second picture pixel; and specifying a change of the picture signal from one picture pixel to a next picture pixel in a predeterminable phase relationship relative to the system clock pulse.
In accordance with an additional feature of the invention, there are the steps of: feeding a further picture signal and a selection signal to the display system; displaying the picture signal and the further picture signal on the display by the display system in dependence on the selection signal; and changing the selection signal in a predeterminable further phase relationship relative to the system clock pulse.
In accordance with another feature of the invention, there is the step of sampling the picture signal resulting in a sampled value and subsequently displaying the sampled value where an instant of sampling is specified in dependence on the system clock pulse.
In accordance with a concomitant feature of the invention, there are the steps of: specifying the picture signal as a value for at least one first picture pixel; subsequently specifying the picture signal as a value for at least one second picture pixel; and changing the value of the picture signal from the value for the first picture pixel to the value for the second picture pixel in a predeterminable phase relationship relative to the instant of sampling.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a display system and method for supplying a display system with a picture signal, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.